GRIN Lens Collimators for Cavity Enhanced Absorption Spectroscopy
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Solution Overview
Problem
Current cavity enhanced absorption spectroscopy (CEAS) systems are limited by the size of optical components, which restricts the number of lasers that can be used for measuring multiple gas species and increases self-interference noise, affecting the accuracy and noise ratio of gas concentration measurements.
Innovation Solution
The use of gradient-index (GRIN) lenses as collimators reduces the initial beam size and mass of optical components, allowing for a larger number of lasers to be integrated into the system, thereby increasing the number of measurable gas peaks and improving the signal-to-noise ratio by minimizing self-interference noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional spherical or aspheric refractive lens collimators are used, then the optical components can effectively collimate the laser beam, but the lens size and mass increase, which limits the number of lasers that can be integrated and increases self-interference noise
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional spherical or aspheric refractive lenses to gradient-index (GRIN) lenses, which have a refractive index that varies radially from the optical axis. This parameter change in the lens design enables smaller lens diameter and length while maintaining effective collimation, thereby reducing optical component mass and initial beam size, which reduces self-interference noise and improves signal-to-noise ratio
Solution Approach 2:
The patent replaces the conventional mechanical lens design (spherical or aspheric refractive lenses) with an optical field-based solution using GRIN lenses that utilize gradient refractive index distribution. This substitution allows for compact lens geometry with reduced diameter and length, enabling integration of multiple lasers while minimizing self-interference effects
2Adaptability or versatility
If the number of lasers is increased to measure multiple gas species, then more gas peaks can be measured simultaneously, but the system size and complexity increase due to larger lens and mounting requirements
Solution Approach 1:
The patent utilizes parameter changes in lens design (switching to GRIN lenses with gradient refractive index) to reduce the size of optical components and mounting hardware. This size reduction enables integration of a larger number of lasers into the CEAS system, allowing simultaneous measurement of multiple gas species without proportionally increasing system complexity
Solution Approach 2:
The patent implements multi-functionality by using GRIN lenses that serve multiple purposes: they collimate laser beams effectively, reduces initial beam size, minimize self-interference noise, and enable compact mounting. This universal solution supports integration of multiple lasers with different wavelengths for measuring various gas species within a unified compact system
3Stability of the object's composition
If larger diameter lenses are used to reduce beam divergence, then the beam can be better collimated, but the initial beam size increases, which increases self-interference noise
Solution Approach 1:
The patent applies parameter changes by using GRIN lenses with specific gradient refractive index profiles that achieve effective beam collimation with smaller lens diameters. This parameter change in lens design allows for reduced initial beam size while maintaining collimation quality, thereby reducing self-interference noise that occurs when beams reflect back and forth within the cavity
Solution Approach 2:
The patent converts the potential harm of small lens size (which would normally result in poor collimation) into a benefit by using GRIN lens technology. The gradient refractive index design compensates for the smaller aperture, achieving both compact size and effective collimation, thereby transforming what would be a disadvantage into an advantage for reducing self-interference
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implementation of GRIN lenses enables more gas peaks to be measured simultaneously with improved signal-to-noise ratio and reduced noise, allowing for smaller sample sizes without compromising performance, and allows for a more compact CEAS system design.
Implementation Method 1
The use of gradient index (GRIN) lenses as collimators reduces the initial beam size
Implementation Method 2
gradient-index (GRIN) lenses as an optical component of the CEAS system
Implementation Method 3
a gas cell enclosed by a first mirror on one end of the gas cell and a second mirror on the other end of the gas cell to form a cavity therein
Implementation Method 4
cavity enhanced absorption spectroscopy (CEAS) to measure composition of a sample of gas
Implementation Method 5
Accurately measuring gas concentration using CEAS requires analyzing one or more absorption peaks
Data Source
AI summary
A cavity enhanced absorption spectroscopy (CEAS) system is provided that utilizes collimators the incorporate gradient index (GRIN) lenses in lieu of conventional spherical or aspheric refractive lenses. The use of smaller diameter GRIN lenses facilitates a reduced initial beam size entering the sample cavity, which reduces self-interference noise and increases a signal to noise ratio of the measurements. Further, a reduced size and mass of the GRIN lens can reduce a size of the mounting hardware utilized to mount the optical components, which enables more laser beams to be coupled to a single gas cell compared to a similar gas cell integrated with conventional refractive collimators. A larger number of lasers enables more gas peaks to be measured substantially simultaneously using the CEAS system.